Novel motor autotransformer step-down starting control circuit

Abstract

The utility model discloses a novel motor autotransformer step-down starting control circuit. The system comprises a star point contactor KM1, a step-down contactor KM2, a full-voltage contactor KM3, a circuit breaker QF, a thermal relay FR, a start button SB2, a stop button SB1, a first time relay KT1, a second time relay KT2, a first intermediate relay KA1, a second intermediate relay KA2, a first indicating lamp HL1, a second indicating lamp HL2, a third indicating lamp HL3, an autotransformer QSA and a motor M. The circuit has the advantages that the second time relay, the second intermediate relay and other elements are additionally arranged in the circuit, so that the full-voltage contactor is enabled to operate after a period of time after the star point contactor and the step-down contactor on the step-down circuit are all de-energized and released; the arc light short circuit phenomenon caused by the simultaneous action of the star point contactor, the step-down contactor and the full-voltage contactor can be avoided, and the stable operation of the circuit is further ensured.

Description

Technical Field:

[0001] The utility model relates to the technical field of motor starting control, and particularly to a novel motor autotransformer step-down starting control circuit. Background Art:

[0002] Autotransformer step-down starting means that when a motor starts, an autotransformer is used to reduce the starting voltage applied to the stator winding of the motor. After the motor starts, the motor is then disconnected from the autotransformer so as to operate normally under full voltage. The existing autotransformer step-down starting control circuit is as Figure 1 shown. Its step-down and full-voltage switching process is as follows: Close the control switch QF, the first contactor KM1 is energized and self-locked, and the coil of the second contactor KM2 is energized - the motor starts with reduced voltage. At the same time, the coil of the time relay KT is energized; when the time relay KT reaches the set time, the normally open timedelay off contact of the time relay KT opens - the coil of the second contactor KM2 loses power - the step-down circuit is disconnected (the step-down contactor is released). At the same time, the normally closed timedelay on contact of the time relay KT closes - the coil of the third contactor KM3 is energized and self-locked - the motor starts with full voltage.

[0003] In the above process, the release of the second contactor KM2 and the energization of the third contactor KM3 occur simultaneously. However, when a contactor fails, there will be a situation where the second contactor KM2 fails to release in time while the third contactor KM3 has already been energized. At this time, for the motor, when the third contactor KM3 is energized, it connects 100% voltage, and when the second contactor KM2 is energized, it connects 80% voltage. When the third contactor KM3 and the second contactor KM2 provide two different voltages to the same motor simultaneously, arc short-circuit will occur, which will cause the switch to trip at the least and the motor to burn out at the worst, affecting production. Content of the Utility Model:

[0004] The purpose of the utility model is to provide a novel motor autotransformer step-down starting control circuit.

[0005] The utility model is implemented by the following technical solutions: a novel motor autotransformer step-down starting control circuit, which includes a neutral point contactor, a step-down contactor, a full-voltage contactor, a circuit breaker, a thermal relay, a start button, a stop button, a first time relay, a second time relay, a first intermediate relay, a second intermediate relay, a first indicator light, a second indicator light, a third indicator light, an autotransformer, and a motor. The start button is connected in parallel with the first normally open contact of the neutral point contactor and then sequentially connected in series with the first normally closed contact of the first intermediate relay and the coil of the neutral point contactor to form a first branch. The first normally closed contact of the step-down contactor is connected in series with the second normally open contact of the neutral point contactor and then connected in parallel with the first normally open contact of the second intermediate relay and then sequentially connected in series with the second normally closed contact of the first intermediate relay and the coil of the second intermediate relay to form a second branch. The second normally open contact of the second intermediate relay is connected in series with the parallel branch of the coil of the first time relay and the coil of the step-down contactor to form a third branch. The power-on delay closing contact of the first time relay, the power-on delay opening contact of the second time relay, and the coil of the first intermediate relay are connected in series to form a fourth branch. The first normally closed contact of the neutral point contactor, the second normally closed contact of the step-down contactor, the first normally open contact of the first intermediate relay, and the coil of the second time relay are connected in series to form a fifth branch. The line between the power-on delay closing contact of the first time relay and the power-on delay opening contact of the second time relay and the line between the first normally open contact of the first intermediate relay and the coil of the second time relay are connected by wires; the first normally closed contact of the full-voltage contactor is first connected in series with the power-on delay closing contact of the second time relay and then connected in parallel with the first normally open contact of the full-voltage contactor and then sequentially connected in series with the second normally closed contact of the neutral point contactor, the second normally closed contact of the step-down contactor, and the coil of the full-voltage contactor to form a sixth branch; the contact of the thermal relay is connected in series with the stop button and then respectively connected in series with the first branch, the second branch, the third branch, the fourth branch, the fifth branch, and the sixth branch and then connected to the power supply. The main contacts of the circuit breaker, the full-voltage contactor, and the thermal relay are connected in series and then connected to the control circuit of the motor. The neutral point of the autotransformer is connected to the main contact of the neutral point contactor. The tap of the autotransformer is connected to the circuit between the main contact of the full-voltage contactor and the thermal relay. The output end of the autotransformer is connected to the circuit between the circuit breaker and the main contact of the full-voltage contactor.

[0006] Further, the contact of the thermal relay, the stop button, the third normally closed contact of the neutral point contactor, and the first indicator light are connected in series and then connected to the power supply.

[0007] Further, one end of the second indicator light is connected to the circuit between the first normally closed contact of the step-down contactor and the second normally open contact of the neutral point contactor, and the other end of the second indicator light is connected to the line between the coil of the second intermediate relay and the power supply.

[0008] Further, one end of the third indicator light is connected to the line between the first normally closed contact of the full-voltage contactor and the power-on delay closing contact of the second time relay, and the other end of the third indicator light is connected to the line between the coil of the full-voltage contactor and the power supply.

[0009] Advantages of the present utility model: Components such as a second time relay and a second intermediate relay are added to the circuit, which can ensure that after the star-point contactor and the step-down contactor on the step-down circuit are all de-energized and released, the full-voltage contactor is energized and operated after a period of time, thus preventing the occurrence of arcing short circuit phenomena caused by the simultaneous operation of the star-point contactor, the step-down contactor, and the full-voltage contactor, and further ensuring the stable operation of the circuit. Moreover, indicator lights for displaying the operating states of the star-point contactor, the step-down contactor, and the full-voltage contactor are added to the circuit, which play a warning role and are convenient for troubleshooting. Description of the drawings:

[0010] Figure 1 It is the existing autotransformer step-down starting control circuit in the background art.

[0011] Figure 2 It is the control circuit of the present utility model.

[0012] Figure 3 It is the main control diagram of the present utility model.

[0013] Star-point contactor KM1, step-down contactor KM2, full-voltage contactor KM3, circuit breaker QF, thermal relay FR, start button SB2, stop button SB1, first time relay KT1, second time relay KT2, first intermediate relay KA1, second intermediate relay KA2, first indicator light HL1, second indicator light HL2, third indicator light HL3, autotransformer QSA, motor M; Specific implementation manner:

[0014] In the description of the present utility model, it should be noted that when terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to the present utility model. In addition, when terms such as "first", "second", "third" appear, they are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0015] Such as Figure 2 and Figure 3As shown in the figure, a new type of motor autotransformer step-down starting control circuit includes a neutral point contactor KM1, a step-down contactor KM2, a full-voltage contactor KM3, a circuit breaker QF, a thermal relay FR, a start button SB2, a stop button SB1, a first time relay KT1, a second time relay KT2, a first intermediate relay KA1, a second intermediate relay KA2, a first indicator light HL1, a second indicator light HL2, a third indicator light HL3, an autotransformer QSA, and a motor M. The start button SB2 is connected in parallel with the first normally open contact of the neutral point contactor KM1, and then is successively connected in series with the first normally closed contact of the first intermediate relay KA1 and the coil of the neutral point contactor KM1 to form a first branch. The first normally closed contact of the step-down contactor KM2 is connected in series with the second normally open contact of the neutral point contactor KM1, and then is connected in parallel with the first normally open contact of the second intermediate relay KA2, and then is successively connected in series with the second normally closed contact of the first intermediate relay KA1 and the coil of the second intermediate relay KA2 to form a second branch. The second normally open contact of the second intermediate relay KA2 is connected in series with the parallel branch of the coil of the first time relay KT1 and the coil of the step-down contactor KM2 to form a third branch. The power-on delay closing contact of the first time relay KT1, the power-on delay opening contact of the second time relay KT2, and the coil of the first intermediate relay KA1 are connected in series to form a fourth branch. The first normally closed contact of the neutral point contactor KM1, the second normally closed contact of the step-down contactor KM2, the first normally open contact of the first intermediate relay KA1, and the coil of the second time relay KT2 are connected in series to form a fifth branch. The line between the power-on delay closing contact of the first time relay KT1 and the power-on delay opening contact of the second time relay KT2 and the line between the first normally open contact of the first intermediate relay KA1 and the coil of the second time relay KT2 are connected by wires; the first normally closed contact of the full-voltage contactor KM3 is first connected in series with the power-on delay closing contact of the second time relay KT2, and then is connected in parallel with the first normally open contact of the full-voltage contactor KM3, and then is successively connected in series with the second normally closed contact of the neutral point contactor KM1, the second normally closed contact of the step-down contactor KM2, and the coil of the full-voltage contactor KM3 to form a sixth branch; the contact of the thermal relay FR is connected in series with the stop button SB1, and then is respectively connected in series with the first branch, the second branch, the third branch, the fourth branch, the fifth branch, and the sixth branch and then connected to the power supply. The main contacts of the circuit breaker QF and the full-voltage contactor KM3 are connected in series with the thermal relay FR and then connected to the control circuit of the motor M. The neutral point of the autotransformer QSA is connected to the main contact of the neutral point contactor KM1. The tap of the autotransformer QSA is connected to the circuit between the main contact of the full-voltage contactor KM3 and the thermal relay FR. The output end of the autotransformer QSA is connected to the circuit between the circuit breaker QF and the main contact of the full-voltage contactor KM3.

[0016] The contacts of the thermal relay FR, the stop button SB1, the third normally closed contact of the star contactor KM1, and the first indicator light HL1 are connected in series and then connected to the power supply.

[0017] One end of the second indicator light HL2 is connected to the circuit between the first normally closed contact of the step-down contactor KM2 and the second normally open contact of the star contactor KM1, and the other end of the second indicator light HL2 is connected to the line between the coil of the second intermediate relay KA2 and the power supply.

[0018] One end of the third indicator light HL3 is connected to the line between the first normally closed contact of the full-voltage contactor KM3 and the power-on delay closing contact of the second time relay KT2, and the other end of the third indicator light HL3 is connected to the line between the coil of the full-voltage contactor KM3 and the power supply.

[0019] Control process:

[0020] Close the circuit breaker QF, press the start button SB2, the coil of the star contactor KM1 gets energized and self-locks, and the star point of the autotransformer QSA is connected; all the normally open contacts of the star contactor KM1 are closed - the coil of the second intermediate relay gets energized and self-locks - the coil of the step-down contactor KM2 gets energized, and the first time relay KT1 starts timing at the same time. The main contacts of the step-down contactor KM2 are closed - the motor M starts running at reduced voltage. When the time set by the first time relay KT1 is reached, its power-on delay closing contact is closed - the first intermediate relay KA1 gets energized;

[0021] The coil of the first intermediate relay KA1 gets energized, and its normally closed contact opens - the coil of the star contactor KM1 loses power, and the coil of the second intermediate relay KA2 loses power - the normally open contact of the second intermediate relay KA2 opens - the coil of the step-down contactor KM2 loses power - the main contacts of the step-down contactor KM2 are released, and the normally closed contact of the star contactor KM1 is closed, and the normally closed contact of the step-down contactor KM2 is closed - the coil of the first intermediate relay KA1 gets energized and self-locks and the coil of the second time relay KT2 gets energized and starts timing;

[0022] When the time set by KT2 is reached, its power-on delay closing contact is closed - the coil of the full-voltage contactor KM3 gets energized and self-locks - the main contacts of KM3 are closed - the motor M runs at full voltage.

[0023] Before starting the motor, if the first indicator light HL1 is on, it means the star contactor KM1 is normal; if the second indicator light HL2 is on, it means the step-down contactor KM2 is normal; if the third indicator light HL3 is on, it means the full-voltage contactor KM3 is normal; on the contrary, if any indicator light is not on before starting the motor, it means the corresponding contactor has a fault and starting is prohibited, which is used to prompt the staff to repair in time.

[0024] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A novel motor autotransformer step-down starting control circuit, characterized in that: It includes a star point contactor (KM1), a step-down contactor (KM2), a full-voltage contactor (KM3), a circuit breaker (QF), a thermal relay (FR), a start button (SB2), a stop button (SB1), a first time relay (KT1), a second time relay (KT2), ​​a first intermediate relay (KA1), a second intermediate relay (KA2), a first indicator light (HL1), a second indicator light (HL2), a third indicator light (HL3), an autotransformer (QSA), a motor (M), a start button (SB2) and a first contactor of the star point contactor (KM1). The normally open contacts are connected in parallel and then connected in series with the first normally closed contact of the first intermediate relay (KA1) and the coil of the star point contactor (KM1) to form a first branch; the first normally closed contact of the step-down contactor (KM2) is connected in series with the second normally open contact of the star point contactor (KM1) and then connected in parallel with the first normally open contact of the second intermediate relay (KA2) and then connected in series with the second normally closed contact of the first intermediate relay (KA1) and the coil of the second intermediate relay (KA2) to form a second branch; the second normally open contact of the second intermediate relay (KA2) is connected in series with the coil of the first time relay (KT1) and the step-down contact (KM1) to form a second branch. The parallel branches of the coils of the pressure contactor (KM2) are connected in series to form a third branch, the power-on delay closing contact of the first time relay (KT1), the power-on delay opening contact of the second time relay (KT2), ​​and the coil of the first intermediate relay (KA1) are connected in series to form a fourth branch, the first normally closed contact of the star point contactor (KM1), the second normally closed contact of the step-down contactor (KM2), the first normally open contact of the first intermediate relay (KA1), and the coil of the second time relay (KT2) are connected in series to form a fifth branch, the power-on delay closing contact of the first time relay (KT1) and the power-on delay disconnecting contact of the first intermediate relay (KA1) are connected in series to form a fifth branch. The circuit between the power-on delay disconnection contacts of the two time relays (KT2) and the circuit between the first normally open contact of the first intermediate relay (KA1) and the coil of the second time relay (KT2) are connected through electric wires; the first normally closed contact of the full-voltage contactor (KM3) is first connected in series with the power-on delay closing contact of the second time relay (KT2), ​​then connected in parallel with the first normally open contact of the full-voltage contactor (KM3), and then connected in series with the second normally closed contact of the star point contactor (KM1), the second normally closed contact of the step-down contactor (KM2), and the coil of the full-voltage contactor (KM3) in sequence to form a sixth branch;The contact of the thermal relay (FR) is connected in series with the stop button (SB1), and then connected in series with the first branch, the second branch, the third branch, the fourth branch, the fifth branch, and the sixth branch, and then connected to the power supply. The main contacts of the circuit breaker (QF) and the full-voltage contactor (KM3) are connected in series with the thermal relay (FR) and then connected to the control circuit of the motor (M). The star point of the autotransformer (QSA) is connected to the main contact of the star point contactor (KM1). The tap of the autotransformer (QSA) is connected to the circuit between the main contact of the full-voltage contactor (KM3) and the thermal relay (FR). The output end of the autotransformer (QSA) is connected to the circuit between the circuit breaker (QF) and the main contact of the full-voltage contactor (KM3). ; 2. A novel motor autotransformer step-down starting control circuit according to claim 1, characterized in that: The contact of the thermal relay (FR), the stop button (SB1), the third normally closed contact of the star point contactor (KM1), and the first indicator light (HL1) are connected in series and then connected to the power supply.

3. A novel motor autotransformer step-down starting control circuit according to claim 1, characterized in that: One end of the second indicator light (HL2) is connected to the circuit between the first normally closed contact of the step-down contactor (KM2) and the second normally open contact of the star point contactor (KM1), and the other end of the second indicator light (HL2) is connected to the line between the coil of the second intermediate relay (KA2) and the power supply.

4. A novel motor autotransformer step-down starting control circuit according to claim 1, characterized in that: One end of the third indicator light (HL3) is connected to a line between a first normally closed contact of a full-voltage contactor (KM3) and a power-on delayed closing contact of a second time relay (KT2), ​​and the other end of the third indicator light (HL3) is connected to a line between a coil of the full-voltage contactor (KM3) and a power supply.

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